为什么它不让我使用相机控制器拍照？
提问于 2020-08-30 16:22:22
我正在尝试使用全屏摄像头创建一个应用程序。实时摄像头提要和按钮反馈一样有效。_controller.takePicture(path)行似乎有问题，因为"IS INITIALIZED“打印语句返回true。我将路径、路径提供程序和相机依赖项放在pubspec.yaml中。
CameraController的初始化
cameras = await availableCameras();
var frontCamera = cameras.first;
_controller = CameraController(frontCamera, ResolutionPreset.high);
try {
await _controller.initialize();
} catch (e) {
}
print('Controller Is Init:' + _controller.value.isInitialized.toString());
displayPreview();child: GestureDetector(
behavior: HitTestBehavior.translucent,
child:Container(
child: Icon(Icons.camera,color: Colors.white,size: 60,)),
onTap: () async {
print('IS INITIALIZED'+_controller.value.isInitialized.toString());
try {
await _controller.takePicture(path);
}
catch(e){
print('E:'+e);
}错误：
E/MethodChannel#plugins.flutter.io/camera(28109): Failed to handle method call
E/MethodChannel#plugins.flutter.io/camera(28109): java.lang.NullPointerException
E/MethodChannel#plugins.flutter.io/camera(28109): at java.io.File.<init>(File.java:283)
E/MethodChannel#plugins.flutter.io/camera(28109): at io.flutter.plugins.camera.Camera.takePicture(Camera.java:227)
E/MethodChannel#plugins.flutter.io/camera(28109): at io.flutter.plugins.camera.MethodCallHandlerImpl.onMethodCall(MethodCallHandlerImpl.java:77)
E/MethodChannel#plugins.flutter.io/camera(28109): at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:230)
E/MethodChannel#plugins.flutter.io/camera(28109): at io.flutter.embedding.engine.dart.DartMessenger.handleMessageFromDart(DartMessenger.java:85)
E/MethodChannel#plugins.flutter.io/camera(28109): at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(FlutterJNI.java:664)
E/MethodChannel#plugins.flutter.io/camera(28109): at android.os.MessageQueue.nativePollOnce(Native Method)
E/MethodChannel#plugins.flutter.io/camera(28109): at android.os.MessageQueue.next(MessageQueue.java:336)
E/MethodChannel#plugins.flutter.io/camera(28109): at android.os.Looper.loop(Looper.java:197)
E/MethodChannel#plugins.flutter.io/camera(28109): at android.app.ActivityThread.main(ActivityThread.java:8125)
E/MethodChannel#plugins.flutter.io/camera(28109): at java.lang.reflect.Method.invoke(Native Method)
E/MethodChannel#plugins.flutter.io/camera(28109): at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:496)
E/MethodChannel#plugins.flutter.io/camera(28109): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1100)
E/flutter (28109): [ERROR:flutter/lib/ui/ui_dart_state.cc(166)] Unhandled Exception: type 'CameraException' is not a subtype of type 'String'
E/flutter (28109): #0 _VisualPageState.build.<anonymous closure> (package:ourearth2020/screens/VisualPage.dart:209:36)
E/flutter (28109): <asynchronous suspension>
E/flutter (28109): #1 _VisualPageState.build.<anonymous closure> (package:ourearth2020/screens/VisualPage.dart)
E/flutter (28109): #2 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:184:24)
E/flutter (28109): #3 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:524:11)
E/flutter (28109): #4 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:284:5)
E/flutter (28109): #5 BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:219:7)
E/flutter (28109): #6 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:477:9)
E/flutter (28109): #7 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:78:12)
E/flutter (28109): #8 PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:124:9)
E/flutter (28109): #9 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
E/flutter (28109): #10 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:122:18)
E/flutter (28109): #11 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:108:7)
E/flutter (28109): #12 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:220:19)
E/flutter (28109): #13 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:200:22)
E/flutter (28109): #14 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:158:7)
E/flutter (28109): #15 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:104:7)
E/flutter (28109): #16 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:88:7)
E/flutter (28109): #17 _rootRunUnary (dart:async/zone.dart:1206:13)
E/flutter (28109): #18 _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter (28109): #19 _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter (28109): #20 _invoke1 (dart:ui/hooks.dart:283:10)
E/flutter (28109): #21 _dispatchPointerDataPacket (dart:ui/hooks.dart:192:5)
回答 1
Stack Overflow用户
发布于 2020-08-31 05:29:14
这看起来像是您作为参数提供的path不是String，而是CameraException。
要创建路径，您可以这样做(需要path_provider)：
final path = (await getTemporaryDirectory()).path + '${DateTime.now()}.png';页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/63659569
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